diff -r 08b2cb94c57c -r db9617c1d01f liststart.rst --- a/liststart.rst Thu Sep 23 11:00:44 2010 +0530 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,160 +0,0 @@ -.. #[Nishanth]: liststart is not a good name. there is no consistency. - Use underscores or hyphens instead of spaces and - make the filename from LO name - Ex: getting_started_with_lists (or) - getting_started_lists - -Hello friends and welcome to the tutorial on getting started with -lists. - - {{{ Show the slide containing title }}} - - {{{ Show the slide containing the outline slide }}} - -In this tutorial we will be getting acquainted with a python data -structure called lists. We will learn : - * How to create lists - * Structure of lists - * Access list elements - * Append elements to lists - * Deleting elements from lists - -.. #[Nishanth]: Did you compile this?? - There must an empty before the bulleted list - -I hope you have ipython running on your system. - -.. #[Nishanth]: need not specify. Implicit that IPython is running - -List is a compound data type, it can contain data of other data -types. List is also a sequence data type, all the elements are in -order and there order has a meaning. - -We will first create an empty list with no elements. On your IPython -shell type :: - - empty = [] - type(empty) - - -This is an empty list without any elements. - -* Filled lists - -Lets now define a list, nonempty and fill it with some random elements. - -nonempty = ['spam', 'eggs', 100, 1.234] - -Thus the simplest way of creating a list is typing out a sequence -of comma-separated values (items) between square brackets. -All the list items need not have the same data type. - -.. #[Nishanth]: do not use "You" or anything else. Stick to "We" - -As we can see lists can contain different kinds of data. In the -previous example 'spam' and 'eggs' are strings and 100 and 1.234 -integer and float. Thus we can put elements of heterogenous types in -lists. Thus list themselves can be one of the element types possible -in lists. Thus lists can also contain other lists. Example :: - - list_in_list=[[4,2,3,4],'and', 1, 2, 3, 4] - -We access list elements using the number of index. The -index begins from 0. So for list nonempty, nonempty[0] gives the -first element, nonempty[1] the second element and so on and -nonempty[3] the last element.:: - - nonempty[0] - nonempty[1] - nonempty[3] - -We can also access the elememts from the end using negative indices :: - - nonempty[-1] - nonempty[-2] - nonempty[-4] - --1 being the last element , -2 second to last and -4 being the first -element. - -.. #[Nishanth]: -1 being last element sounds like -1 is the last element - Instead say -1 gives the last element which is 4 - -.. #[Nishanth]: Instead of saying -4 being the first, say -4 gives 4th - from the last which is the first element. - -* =append= elements -We can append elements to the end of a list using append command. :: - - nonempty.append('onemore') - nonempty.append(6) - nonempty - -As we can see non empty appends 'onemore' and 6 at the end. - -.. #[Nishanth]: First show an example with only one append. - may be show the value of a after first append - then show what happens after second append - -Using len function we can check the number of elements in the list -nonempty. Because we just appended two elements at the end this -returns us 6.:: - - len(nonempty) - -.. #[Nishanth]: the "because ..." can be removed. You can simply - say len gives the no.of elements which is 6 here - -Just like we can append elements to a list we can also remove them. -There are two ways of doing. One is by using index. :: - - del(nonempty[1]) - -.. #[Nishanth]: do not use "You" or anything else. Stick to We - -deletes the element at index 1, i.e the second element of the -list, 'eggs'. The other way is removing element by content. Lets say -one wishes to delete 100 from nonempty list the syntax of the command -should be :: - - a.remove(100) - -but what if their were two 100's. To check that lets do a small -experiment. :: - - a.append('spam') - a - a.remove('spam') - a - -If we check a now we will see that the first occurence 'spam' is removed -thus remove removes the first occurence of the element in the sequence -and leaves others untouched. - - -{{{Slide for Summary }}} - - -In this tutorial we came across a sequence data type called lists. :: - - * We learned how to create lists. - * Append elements to list. - * Delete Element from list. - * And Checking list length. - -.. #[Nishanth]: See the diff. I have corrected punctuation in many places. - The first thing you do before committing is compile the script. - I have corrected syntax errors also in many places. - -{{{ Sponsored by Fossee Slide }}} - -This tutorial was created as a part of FOSSEE project. - -I hope you found this tutorial useful. - -Thank You - - -Author : Amit Sethi -First Reviewer : -Second Reviewer : Nishanth